Die casting method for the manufacture of brushes



March 10, 1953 M. SCHIFFER Er AL 2,630,601

DIE CASTING METHOD FOR THE MANUFACTURE OF BRUSHES Filed July 30, 1951 2 SHEETS-SHEET 1.

(0 R? I w INVENTOR MAXIMILIAN SCHIFFER BY CARL SCHIFFER Patented Mar. 10, 1953 DIE CASTING METHOD FOR THE MANUFACTURE OF BRUSHES Maximilian Schilfer and Carl Schiffer, Rheydt, Germany Application July 30, 1951, Serial N0."239,248

3 Claims. 1

The present invention relates to the manufacture oi brushes, especially fine brushes, such as tooth or nail. brushes and the like, and more particularly to a one-step operation for die casting the brush bristles into the brush body while the body is being cast.

.Die casting methods and apparatus for the manufacture of brushes from synthetic substances, such as thermoplastic or thermosetting resins and the like, are known. It is also known to die cast bore holes in the brush bodies during their manufacture so that the bristles may subsequently be inserted therein. In the known manufacturing processes of this nature, the finished brush bodies are removed from the die casting apparatus and are manually or otherwise transferred to a special bristle insertion machine which mechanically inserts the suitably prepared and cut bristles in the bore holes of the brush bodies.

The known manufacturing methods, as outlined hereinabove, are rather cumbersome, timeconsuming and expensive, particularly since they involve the manual operations of removing the cast brush body from the die casting machine and inserting it in the bristle insertion apparatus.

It is the main object of the present invention to provide an economical and hygienically more perfect method and apparatus for manufacturin brushes.

It is a further object of the invention to make :full use of the bristle material which is fed to the die casting operation in continuous lengths :and utilized without waste.

It is also an object of the invention to eliminate a variety of manufacturing steps and to simplify the operation whereby it is no longer necessary to operate, maintain and feedcurrent to the heretofore used bristle insertion machines, or to make use of the heretofore utilized anchor punching wire for the manufacture of the anchor for the mechanical insertion of the bristles.

In accordance with a feature of the invention, the bristles and brush body are homogeneously jointed so that no dirt can enter where the bristles are anchored to the body. The brushes manufactured according to the present invention are also much sturdier anddurable since the bristles are. more firmlyanchored to the brush body and cannot fall out.

The above and other objects and advantages are obtained in accordance with this invention by simultaneously and in the same die casting operation and machine forming a brush body and anchoring thereto continuous lengths of bristles,

and thereafter severing desired lengths of bristles anchored to the brush from the continuous lengths of bristles supplied to the die casting machine.

The principles and main features of the invention will become more apparent from the following detailed description of a preferred embodiment of an apparatus for practicing the manufacture, taken in conjunction with the accompanying drawing wherein:

Fig. 1 shows a die casting apparatus according to the invention, in section;

Fig. 2 shows a plan view of the die casting apparatus of Fig. 1;

Fig. 2a shows a section along line B-B of Fig. 2 of the bristle clamping mechanism of the apparatus;

Fig. 2b shows a section along line A--A of Fig. 2 of the bristle clamping mechanism of the apparatus;

Fig. 2c is an enlargement of Fig. 2a, .showing the bristle clamped in by the laterally moved plate 5.;

Fig. 3 shows an enlarged detail of Fig. 1; and

Figs. 4 and 5 show a part of the die, in section, during succeeding stages of the process when the casting is removed.

Referring now to Drawing 1, there is shown stationary die plate I and movable die member 2, forming therebetween die forms 3 for the brush bodies, about one half of the depth of the form being embedded in part I and the other half in part 2. The warm mass of the casting material is introduced through cone 4 so that it flows into the form 3. Any thermoplastic or thermosetting material heated to its thermoplastic state may be used in this process, as is well known in the art. These materials form no part of the present invention and are, therefore, not further described. Suitable synthetic resins have been widely used for the manufacture of brush bodies.

Die member 2 comprises parts 32 and 33 which are fixedly secured to each other by means of screw bolts [3. Guide bolts l2 are mounted in member 2 and are adapted slidably to engage suitable guide channels in member I whereby die members and 2 are centered. End plate M is fixedly attached to die member 2 by screws l5.

Die casting box IS with conical bore 4 is mounted in member I (see particularly Fig. 3) and protrudes into the die form 3 almost to half its depth. The part of box is which reaches into form 3 is conically formed whereby there is formed in the cast brush body a recessed portion, as" shown in Fig. 3. Movable die member 2 car- 3 ries, fixedly attached thereto, guide bushings I! and i8, bushin ll protruding into die form 3 opposite box It and being formed with a conical end portion which similar to the conical end portion of box It forms a recessed portion in the brush body. Intermediate space 36 remaining between the two conical ends of box it and bushing I'i, upon closure of the die casting apparatus, is chosen so small that it will aid the flowing of the casting material which is supplied to form 3 under pressure by capillary action. When the casting material becomes cold and solid, there is formed a membrane as dividing wall between the two recessed portions cast into the brush body. Guide bushings I? and i8 carry slidable ejecting pistons it. Before the die members I and 2 are separated from each other, piston is is actuated to pierce membrane 38 and to eject from cone d the remaining casting mass. In this manner, the conventional hole in the end of a brush body is formed in the same casting operation.

Ejecting piston is is soldered or otherwise fixedly secured in plate which is mounted on plate H by means of screws 22. Plate 22 carries bolt 23 which is slidable in a central bore in end plate M and is connected to plate 25 by means of end screw 2d. Spring means 26 is provided between end plate i l and plate 25, said spring having the tendency of keeping ejection mechanism i9, 26, El, 22, 23, 2e and 25 outside of form 3.

In accordance with the invention, pre-formed bristles of a suitable synthetic substance compatible with the substance of the brush body are introduced in die member 2 simultaneously with the die casting of the brush body and the two synthetic substances are firmly jointed during the die casting process.

The means for inserting the bristles are arranged in member 2 and comprise clamping plates 5 and 6, each one being provided with a plurality of bores l corresponding to the desired number of bristle bundles. Plate 6 is fixedly mounted in die member 2. Plate 5 is laterally movable, its movements being controlled mechanically by the die casting machine or, as shown in Fig. 2, electromagnetically by means of magnet H.

As shown particularly in Figs. 2 and 2a, the magnetic core of magnet H is coupled to bristle clamping plate 5 by means of bolt 28. When cur-- rent is supplied to magnet ii, plate 5 is moved by the magnetic core coupled thereto in the direction of pull of the magnet and the bristle bundles will be clamped between plate 5 and plate 6, as shown in Fig. 20. Spring 29, secured to member 2 by means of screw 3 I, will be tensioned by the lateral movement of plate 5 and, as soon as the magnet is deenergized, spring 29 will pull back plate 5 to its original position, whereby the bristles will again be able to move freely through the bore holes '5.

Die member 2 also carries the guide support 3 for knife it whose cutting motion is controlled mechanically or electrically by the die casting machine when the member 2 is lifted. Knife id is heated by heating plate 8, preferably by electrical means.

The synthetic bristles are supplied to the apparatus in continuous lengths from storage and feed rolls (not shown). Each r011 carries a strand of several bristle filaments, the strands having the same diameter as the desired bristle bundles to be jointed to the brush body. The strands are fed through bores l of plates 5 and 6, the number of bristle strands or bundles depending on the kind of brush to be produced. The bristle bundles are introduced in the machine while die member 2 is lifted up. Any protruding bristle filaments are cut and melted down to the desired casting depth .1: by actuating heated knife M which simultaneously melts together the ends of the synthetic filaments in the individual bristle strands or bundles. Clamping plate 5 is then moved laterally by attraction to energized electromagnet H whereby the bristle bundles are clamped firmly between plates 5 and 6. Thereupon, the die members I and 2 are closed and the casting process is initiated.

As soon as the die casting process is finished, the die casting head (not shown) is automatically moved laterally away from casting box It while the members I and 2 remain closed. Stop 2? is operatively connected to and follows the movement of the die casting head and actuated plate 25 and the ejecting pistons l9, hereinabove described. After the ejecting pistons have pierced membrane 30 and ejected the casting mass remaining in cone 4, stop 2! moves away again from the ejecting mechanism while, simultaneously, the casting head (not shown) moves into casting position in registration with box H5. The tensioned spring 26 is freed and the ejecting mechanism returns to its original position.

When the casting is ready to be removed, die member 2 is retracted, the current to magnet H having meanwhile been cut off so that the bristle bundles are no longer clamped between plates 5 and B. As die member 2 is retracted, it glides without restriction over the bristle bundles in bores 7. As soon as the desired bristle length is reached, the bundles are clamped in again by actuation of magnet I I (see Fig. 4). Die member 2 is then farther retracted and causes the cast brush to be lifted from stationary die plate i (see Fig. 5). At the same time, the heated knife IE) is actuated again so: as to cut the finished brush oi the lengths of bristle strands protruding through bores I. The heated knife severs the bristle filaments by melting them and simultaneously melts together the ends of the bristle filaments of the bundles. The brush then falls out of the machine which is set for the next die casting operation, as outlined hereinabove, i. e. the two die members are brought together again, the clamped together plates 5 and t pull additional lengths of bristle strands from the feed rolls which enter the forms 3 and are there united with the brush bodies during the die casting operation.

The brushes produced in the one-step operation of this invention, as hereinabove described, are then submitted to the conventional after treatment in the known bristle cutting machines. In these machines, the bristles are fashioned to their desired profiles in a simple operation well known in the trade.

While the invention has been described with reference to the now preferred embodiment shown in the drawing, it is to be clearly understood that the same has been given merely for the purposes of illustration and not as a limitation upon the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

l. A method-for the continuous manufacture of brushes, which comprises the following sequence of steps: ploviding a supply of continuous lengths of bristles, introducing and intermittently feeding said lengths of bristles into, a movable firstdie part having perforations forzthe bristles, fixedly holding said bristles in said perforations with the bristles ends projecting beyond the movable first die part, cutting said ends to provide a predetermined length of bristles projecting beyond said movable first die part, placing said movable first die part with the bristles fixedly held therein over a second die part having a surface spaced from the movable first die part to obtain a closed die form, filling the die form with plastic material to die cast a brush body around said bristles, letting the plastic material harden, releasing the bristles die cast into the brush body from their fixed hold in the movable first die part perforations, removing the movable first die part from the second die part with the movable first die part gliding over the released bristles, again fixedly holding the bristles in the movable first die part upon said part having reached a predetermined distance from the brush body, said distance corresponding approximately to the desired bristle lengths on the brush, further moving the movable first die part from the second die part to lift the brush body die cast around the bristles out of the second die part, and cutting the bristles,

2. A method for the continuous and automatic manufacture of brushes, which comprises the following sequence of steps: providing a supply of continuous lengths of thermoplastic bristles, introducing and intermittently feeding said lengths of bristles into a movable die part having perforations for the bristles, clamping said bristles in said perforations with the bristles ends projecting beyond the movable die part, cutting said ends to provide a predetermined length of bristles projecting beyond said movable die part and simultaneously melting said ends to provide little bristle heads, placing said movable die part with the bristles clamped therein over a stationary die part having a surface spaced from the surface of the movable die part to obtain a closed die form, causing a thermoplastic material to flow into the die form in the form of a membrane to fill the die form and die cast a brush body around said bristles, letting the thermoplastic material harden, releasing the bristles die cast into the brush body from being clamped in the movable die part, removing the movable die part from the stationary die part with the movable die part gliding over the released bristles, again clamping the bristles in the movable die part upon said part having reached a predetermined distance from the brush body, said distance approximately corresponding to the desired bristle lengths on the brush, further moving the movable die part from the stationary die part to lift the brush body die cast around the bristles out of the stationary die part, cutting the bristles to said desired bristle lengths and simultaneously melting the ends of the bristles along the cutting plane to provide little bristle heads, the brush body with its bristles being removed, and continuing the process by placing said movable die part with the bristles clamped therein over said stationary die part to manufacture brushes in a continuous manner until the continuous supply of bristles is exhausted.

3. A method for the continuous and automatic manufacture of brushes, which consists essentially of the following sequence of steps, all steps being automatically coordinated: providing a supply of continuous lengths of bristles of a heatactivatable material, introducing and intermittently feeding said lengths of bristles into a movable die part having perforations for the bristles, clamping said bristles in said perforations with the bristles ends projecting beyond the movable die part, cutting said ends to provide a predetermined length of bristles projecting beyond said movable die part and simultaneously melting said ends to provide littlebristle heads, placing said movable die part with the bristles clamped therein over a stationary die part having a surface spaced from the surface of the movable die part to obtain a closed die form, causing a thermoplastic material to flow into the die form in the form of a membrane to fill the die form and die cast a brush body around said bristles, letting the thermoplastic material harden, ejecting the hardened membrane of the brush body formed at the entrance of the thermoplastic material into the die form, said ejection being effected in a direction opposite to that of the flow of the thermoplastic material, thus forming a bore in the brush body, releasing the bristles die cast into the brush body from being clamped in the movable die part, removing the movable die part from the stationary die part with the movable die part gliding over the released bristles, again clamping the bristles in the movable die part upon said part having reached a predetermined distance from the brush body, said distance approximately corresponding to the desired bristle lengths of the brush, further moving the movable die part from the stationary die part to lift the brush body die cast around the bristles out of the stationary part, cutting the bristles to said desired bristle lengths and simultaneously melting the ends of the bristles along the cutting plane to provide little bristle heads, removing the brush body with its bristles die cast therein, and continuing the process by placing said movable die part with the bristles clamped therein over said stationary die part to manufacture brushes in a continuous and automatic manner until the continuous supply of bristles is exhausted.

M. SCHIFFER. CARL SCHIFFER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,010,788 Nordfors Dec. 5, 1911 1,265,808 Morrison May 14, 1918 2,303,800 Swann Dec. 1, 1942 2,317,110 Person Apr. 20, 1943 2,330,369 Marsh Sept. 28, 1943 2,471,148 Gale et al. Mar. 24, 1949 2,494,777 Patterson et al Jan. 17, 1950 OTHER REFERENCES Ser. No. 285,944, Svarovski (A. P. 0.), published April 27, 1943. 

